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	$174.96	12.122%	$196.1687	$196.17	$196.15	$196.20
Purchase #2	$187.78	13.755%	$213.6091	$213.61	$213.60	$213.60
Purchase #3	$95.48	6.673%	$101.8514	$101.85	$101.85	$101.90
Purchase #4	$233.49	12.139%	$261.8334	$261.83	$261.85	$261.80
Purchase #5	$79.85	11.412%	$88.9625	$88.96	$88.95	$89.00
Purchase #6	$30.35	12.541%	$34.1562	$34.16	$34.15	$34.20
Purchase #7	$100.49	5.111%	$105.626	$105.63	$105.65	$105.60
7 purchase totals =	$902.40		$1,002.2073	$1,002.21	$1,002.20	$1,002.30