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	$180.82	8.423%	$196.0505	$196.05	$196.05	$196.10
Purchase #2	$58.79	6.318%	$62.5044	$62.50	$62.50	$62.50
Purchase #3	$9.83	6.528%	$10.4717	$10.47	$10.45	$10.50
Purchase #4	$173.93	5.506%	$183.5066	$183.51	$183.50	$183.50
Purchase #5	$95.52	11.279%	$106.2937	$106.29	$106.30	$106.30
Purchase #6	$239.26	6.215%	$254.13	$254.13	$254.15	$254.10
Purchase #7	$244.61	9.698%	$268.3323	$268.33	$268.35	$268.30
7 purchase totals =	$1,002.76		$1,081.2892	$1,081.28	$1,081.30	$1,081.30