Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$192.65	6.695%	$205.5479	$205.55	$205.55	$205.50
Purchase #2	$157.28	3.375%	$162.5882	$162.59	$162.60	$162.60
Purchase #3	$146.33	3.476%	$151.4164	$151.42	$151.40	$151.40
Purchase #4	$208.80	5.681%	$220.6619	$220.66	$220.65	$220.70
Purchase #5	$73.65	13.397%	$83.5169	$83.52	$83.50	$83.50
Purchase #6	$134.83	5.404%	$142.1162	$142.12	$142.10	$142.10
Purchase #7	$213.41	7.343%	$229.0807	$229.08	$229.10	$229.10
7 purchase totals =	$1,126.95		$1,194.9282	$1,194.94	$1,194.90	$1,194.90