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	$99.51	7.478%	$106.9514	$106.95	$106.95	$107.00
Purchase #2	$29.41	7.226%	$31.5352	$31.54	$31.55	$31.50
Purchase #3	$152.74	6.243%	$162.2756	$162.28	$162.30	$162.30
Purchase #4	$152.27	5.167%	$160.1378	$160.14	$160.15	$160.10
Purchase #5	$212.67	9.695%	$233.2884	$233.29	$233.30	$233.30
Purchase #6	$41.55	9.321%	$45.4229	$45.42	$45.40	$45.40
Purchase #7	$60.86	10.159%	$67.0428	$67.04	$67.05	$67.00
7 purchase totals =	$749.01		$806.6541	$806.66	$806.70	$806.60