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	$208.69	7.472%	$224.2833	$224.28	$224.30	$224.30
Purchase #2	$38.98	11.729%	$43.552	$43.55	$43.55	$43.60
Purchase #3	$218.32	7.441%	$234.5652	$234.57	$234.55	$234.60
Purchase #4	$205.54	13.390%	$233.0618	$233.06	$233.05	$233.10
Purchase #5	$50.42	11.669%	$56.3035	$56.30	$56.30	$56.30
Purchase #6	$83.69	5.427%	$88.2319	$88.23	$88.25	$88.20
Purchase #7	$168.74	7.495%	$181.3871	$181.39	$181.40	$181.40
7 purchase totals =	$974.38		$1,061.3848	$1,061.38	$1,061.40	$1,061.50