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	$162.61	7.266%	$174.4252	$174.43	$174.45	$174.40
Purchase #2	$171.28	10.643%	$189.5093	$189.51	$189.50	$189.50
Purchase #3	$219.56	4.467%	$229.3677	$229.37	$229.35	$229.40
Purchase #4	$73.55	6.658%	$78.447	$78.45	$78.45	$78.40
Purchase #5	$247.96	10.556%	$274.1347	$274.13	$274.15	$274.10
Purchase #6	$96.45	3.570%	$99.8933	$99.89	$99.90	$99.90
Purchase #7	$70.44	11.672%	$78.6618	$78.66	$78.65	$78.70
7 purchase totals =	$1,041.85		$1,124.4390	$1,124.44	$1,124.45	$1,124.40