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	$206.98	7.143%	$221.7646	$221.76	$221.75	$221.80
Purchase #2	$76.44	12.667%	$86.1227	$86.12	$86.10	$86.10
Purchase #3	$136.31	10.114%	$150.0964	$150.10	$150.10	$150.10
Purchase #4	$109.91	9.455%	$120.302	$120.30	$120.30	$120.30
Purchase #5	$173.80	13.200%	$196.7416	$196.74	$196.75	$196.70
Purchase #6	$196.55	13.689%	$223.4557	$223.46	$223.45	$223.50
Purchase #7	$61.60	4.866%	$64.5975	$64.60	$64.60	$64.60
7 purchase totals =	$961.59		$1,063.0805	$1,063.08	$1,063.05	$1,063.10