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	$122.50	3.594%	$126.9027	$126.90	$126.90	$126.90
Purchase #2	$11.63	5.808%	$12.3055	$12.31	$12.30	$12.30
Purchase #3	$216.48	11.608%	$241.609	$241.61	$241.60	$241.60
Purchase #4	$220.75	3.504%	$228.4851	$228.49	$228.50	$228.50
Purchase #5	$165.53	5.675%	$174.9238	$174.92	$174.90	$174.90
Purchase #6	$219.80	4.290%	$229.2294	$229.23	$229.25	$229.20
Purchase #7	$72.42	11.700%	$80.8931	$80.89	$80.90	$80.90
7 purchase totals =	$1,029.11		$1,094.3486	$1,094.35	$1,094.35	$1,094.30