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	$82.40	3.715%	$85.4612	$85.46	$85.45	$85.50
Purchase #2	$235.63	13.429%	$267.2728	$267.27	$267.25	$267.30
Purchase #3	$150.74	9.864%	$165.609	$165.61	$165.60	$165.60
Purchase #4	$181.84	9.637%	$199.3639	$199.36	$199.35	$199.40
Purchase #5	$211.52	5.651%	$223.473	$223.47	$223.45	$223.50
Purchase #6	$25.89	9.415%	$28.3275	$28.33	$28.35	$28.30
Purchase #7	$32.83	6.449%	$34.9472	$34.95	$34.95	$34.90
7 purchase totals =	$920.85		$1,004.4546	$1,004.45	$1,004.40	$1,004.50