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	$200.44	5.301%	$211.0653	$211.07	$211.05	$211.10
Purchase #2	$184.79	4.431%	$192.978	$192.98	$193.00	$193.00
Purchase #3	$69.56	12.596%	$78.3218	$78.32	$78.30	$78.30
Purchase #4	$89.82	7.440%	$96.5026	$96.50	$96.50	$96.50
Purchase #5	$98.27	4.302%	$102.4976	$102.50	$102.50	$102.50
Purchase #6	$57.87	3.811%	$60.0754	$60.08	$60.10	$60.10
Purchase #7	$245.64	11.747%	$274.4953	$274.50	$274.50	$274.50
7 purchase totals =	$946.39		$1,015.9360	$1,015.95	$1,015.95	$1,016.00