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	$22.52	12.544%	$25.3449	$25.34	$25.35	$25.30
Purchase #2	$179.57	6.572%	$191.3713	$191.37	$191.35	$191.40
Purchase #3	$194.41	6.644%	$207.3266	$207.33	$207.35	$207.30
Purchase #4	$245.48	3.134%	$253.1733	$253.17	$253.15	$253.20
Purchase #5	$164.47	4.799%	$172.3629	$172.36	$172.35	$172.40
Purchase #6	$74.83	4.512%	$78.2063	$78.21	$78.20	$78.20
Purchase #7	$183.44	9.167%	$200.2559	$200.26	$200.25	$200.30
7 purchase totals =	$1,064.72		$1,128.0412	$1,128.04	$1,128.00	$1,128.10