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	$182.96	10.314%	$201.8305	$201.83	$201.85	$201.80
Purchase #2	$223.30	11.134%	$248.1622	$248.16	$248.15	$248.20
Purchase #3	$193.89	11.542%	$216.2688	$216.27	$216.25	$216.30
Purchase #4	$82.51	9.729%	$90.5374	$90.54	$90.55	$90.50
Purchase #5	$141.63	7.501%	$152.2537	$152.25	$152.25	$152.30
Purchase #6	$99.27	7.232%	$106.4492	$106.45	$106.45	$106.40
Purchase #7	$72.85	3.451%	$75.3641	$75.36	$75.35	$75.40
7 purchase totals =	$996.41		$1,090.8659	$1,090.86	$1,090.85	$1,090.90