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	$175.53	9.428%	$192.079	$192.08	$192.10	$192.10
Purchase #2	$146.31	3.290%	$151.1236	$151.12	$151.10	$151.10
Purchase #3	$230.44	13.833%	$262.3168	$262.32	$262.30	$262.30
Purchase #4	$72.37	8.532%	$78.5446	$78.54	$78.55	$78.50
Purchase #5	$218.84	5.631%	$231.1629	$231.16	$231.15	$231.20
Purchase #6	$66.99	11.824%	$74.9109	$74.91	$74.90	$74.90
Purchase #7	$149.93	4.640%	$156.8868	$156.89	$156.90	$156.90
7 purchase totals =	$1,060.41		$1,147.0246	$1,147.02	$1,147.00	$1,147.00