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	$41.45	5.412%	$43.6933	$43.69	$43.70	$43.70
Purchase #2	$228.51	5.241%	$240.4862	$240.49	$240.50	$240.50
Purchase #3	$67.74	13.528%	$76.9039	$76.90	$76.90	$76.90
Purchase #4	$180.33	4.320%	$188.1203	$188.12	$188.10	$188.10
Purchase #5	$25.71	8.104%	$27.7935	$27.79	$27.80	$27.80
Purchase #6	$72.88	4.479%	$76.1443	$76.14	$76.15	$76.10
Purchase #7	$56.53	8.154%	$61.1395	$61.14	$61.15	$61.10
7 purchase totals =	$673.15		$714.2810	$714.27	$714.30	$714.20