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	$201.88	6.510%	$215.0224	$215.02	$215.00	$215.00
Purchase #2	$98.41	13.871%	$112.0605	$112.06	$112.05	$112.10
Purchase #3	$31.75	6.681%	$33.8712	$33.87	$33.85	$33.90
Purchase #4	$167.65	8.260%	$181.4979	$181.50	$181.50	$181.50
Purchase #5	$222.43	6.603%	$237.1171	$237.12	$237.10	$237.10
Purchase #6	$155.52	9.610%	$170.4655	$170.47	$170.45	$170.50
Purchase #7	$73.87	6.199%	$78.4492	$78.45	$78.45	$78.40
7 purchase totals =	$951.51		$1,028.4838	$1,028.49	$1,028.40	$1,028.50